Blindtrustand‘all-knowingboxes’

An estimated 49-million navigation devices, including in-car systems, portable and handheld units and smart phones, will be in use in the United States this year, says Telematics Research Group in Minnetonka, Minn.

They'll take you off-roading

During a vacation in northern Wisconsin, Hill Wright turned to "Jack"

for directions. "Jack" is the name given to the disembodied voice of his satellite navigation device by the GPS maker. "Jack" sent Wright off the highway and onto a paved road. The road turned first into gravel and then into a dirt trail littered with boulders and covered with overhanging branches. Wright, 48, says he dutifully followed the directions, which turned into a three-hour detour. "When people buy these things,"

he says, "they think they are all-knowing boxes."

They'll drive you off a cliff

Norman Sussman recently queried his GPS for an alternate route home after hitting traffic outside Santa Fe, N.M. Following the machine's directions, he veered up a winding mountain road, expecting to rejoin the interstate. After a half-hour of hairpin turns, Sussman stepped on the brakes: The road ended at a guardrail and a 200-foot cliff. "It looked like a small version of the Grand Canyon," he says.

They'll take you the wrong way

In Dyke, Va., Stone Mountain Vineyards says it has had so many complaints from visitors who have been led astray by high-tech directions that it recently added a note to its Web site: "Warning: Please follow the driving directions on the Web page. If you use GPS, or services such as MapQuest or Google maps, they WILL send you the wrong way!"

They'll take you where it's unsafe

The North Yorkshire County Council in England has put up signs at the entrance to a gravel track declaring it "unsuitable for motor vehicles" after navigation systems had sent drivers on it as a shortcut between two valleys. The rough road quickly turns stony with steep drops in some places, and locals have had to help cars turn around.

They'll make you forget the 'good ole days'

Nick Champion was following directions from "Jill," the voice of his car's GPS device, to a seminar in Long Beach, Calif., when he wound up on a park road that was blocked off by a gate. He backed up and made a

U-turn, and then Jill said she was "recalculating" and directed him back to the park road. He finally shut off the device and went to a nearby gas station to ask directions.

Wall Street Journal

Why do we get wrong directions?

Map data companies like Tele Atlas and Navteq have employees in the field recording everything from street names to lane counts and speed limits. To build their map data-bases, which they supply to GPS makers, they also rely on sources including transportation departments, building associations and public records. But this information can become outdated quickly as businesses move or close shop, new roads are built and old ones are closed for repairs. Map data companies say ensuring that information is accurate and up to date is a constant battle. "I always call it the holy grail of digital mapping that the moment something changes in reality, the map would immediately have it in the database," says Tele Atlas CEO and co-founder Alain De Taeye. "Nobody has achieved that, and so far that is pure science fiction."